On 05 Nov 1965 the 173rd Airborne Brigade initiated "Operation Hump", a reconnaissance in force in an area about 15 miles north of Bien Hoa. The 1st Battalion, Royal Australian Regiment, deployed south of the Dong Nai River while the 1st Battalion, 503rd Infantry, conducted a helicopter assault on a LZ northwest of the Dong Nai and Song Be Rivers. Little contact was made through 07 Nov, when B and C Companies settled into a night defensive position southeast of Hill 65, a triple-canopy jungled hill.

At about 0600 on the morning of 08 Nov, C Company began a move northwest toward Hill 65, while B Company moved northeast toward Hill 78. Shortly before 0800, C Company was engaged by a sizable enemy force well dug in to the southern face of Hill 65. At 0845, B Company was directed to wheel in place and proceed toward Hill 65 with the intention of relieving C Company.

B Company reached the foot of Hill 65 at about 0930 and moved up the hill. Three things soon became obvious:

1- There was a very large enemy force in place on the hill;
2- C Company was getting hammered; and
3- By chance, B Company was forcing the enemy's right flank.
Under pressure from B Company's flanking attack the enemy force - most of an NVA regiment - moved to the northwest, whereupon the B Company commander called in air and artillery fires on the retreating troops. B Company halted in place in an effort to locate and consolidate with C Company's platoons, managing to establish a coherent defensive line running around the hilltop from southeast to northwest, but with little cover on the southern side.

Meanwhile, the NVA commander realized that his best chance was to close with the US soldiers so that the 173rd's air and artillery fire could not be effectively employed. He attempted to out-flank the US position atop the hill from both the east and the southwest, moving his troops closer to the Americans. The result was shoulder-to-shoulder attacks up the hillside, hand-to-hand fighting, and isolation of parts of B and C Companies ... but the Americans held against two such attacks. Although the fighting continued after the second massed attack, it reduced in intensity as the NVA commander again attempted to disengage and withdraw. By late afternoon it seemed that contact had been broken off by the enemy, allowing the two companies to prepare a night defensive position while collecting their dead and wounded in the center of the position. Although a few of the most seriously wounded were extracted by USAF helicopters using Stokes litters, the triple-canopy jungle prevented the majority from being evacuated until the morning of 09 Nov.

The result of the battle was heavy losses on both sides - 50 Skytroopers dead, many more wounded, and 403 dead NVA troops.

Operation Hump is memorialized in a song by Big and Rich named "8th of November".